Thyroid and Parathyroid Glands Lecture Notes PDF

Thyroid and Parathyroid glands Red: important. Black: in male|female slides. Gray: notes|extra. Editing file  OBJECTIVES o Describe the histological structure of THYROID GLAND o Identify and correlate between the different ENDOCRINE CELLS in THYROID GLAND a...

Thyroid and Parathyroid glands Red: important. Black: in male|female slides. Gray: notes|extra. Editing file  OBJECTIVES o Describe the histological structure of THYROID GLAND o Identify and correlate between the different ENDOCRINE CELLS in THYROID GLAND and THEIR FUNCTIONS o The microscopic structure of the PARATHYROID GLAND o The functional structure of the PARATHYROID CELLS Histology team 437 | Endocrine block | Lecture two & three  Thyroid Gland THYROID GLAND PARENCHYMA STROMA THYROID FOLLICLES: 1- Capsule: dense irregular collagenous Are the structural and functional units of C.T. the thyroid gland. 2- Septa (Interlobular septa) L/M: 3- Reticular fibers: 1- Simple cuboidal epithelium: Thin C.T., composed mostly of a- Follicular cells. reticular b- Parafollicular cells. fibers with rich capillary plexus 2- Colloid: central colloid-filled lumen. surrounds Acidophil gel like material each thyroid follicle. Highly vascular to supply the gland with amino acids and N.B. Each follicle is surrounded by thin Iodine basal lamina. Parafollicular cells Follicular cells Colloid Histology team 437 | Endocrine block | Lecture two & three  PARAFOLLICULAR CELLS FOLLICULAR (PRINCIPAL) CELLS (CLEAR CELLS) (C-CELLS) 0.1% of the 99.9% of the cells cells -Pale-stained cells (Clear Cells). -Simple cuboidal cells L/M - Are found singly or in clusters in -Round nucleus with prominent between the follicular cells. nucleoli. - Their apices do not reach the lumen -Basophilic cytoplasm. of the lumen of the follicle. -Are larger than follicular cells -Apical surface reaches (2-3 times). the lumen of the thyroid -Only 0.1% of the epithelial cells. follicle. -Have round nucleus -Mitochondria. - Mitochondria. E/M -RER (moderate). - RER synthesis of thyroglobulin -Well-developed Golgi. - Supranuclear Golgi Complex. - Numerous apically-located lysosomes. - Numerous dispersed small vesicles: contain newly formed thyroglobulin. - Numerous apical short microvilli. Secrete calcitonin. Synthesis of thyroid hormones (T4 & Functio Lysosomes are important because it has peroxidase enzyme which convert reduced iodine to Iodine T3) n The secretory vesicles are Apical in thyroid gland and basal in parathyroid Calcitonin works with parathyroid hormone to balance the level of Ca++ in the blood Histology team 437 | Endocrine block | Lecture two & three  Parathyroid Glands.They are 4 glands on the posterior of thyroid gland Parenchyma Stroma The parenchyma is formed of cords or clusters of epithelial 1- Capsule: Each gland has its cells (chief cells & oxyphil cell) with blood capillaries in Thin capsule. between. These cells are surrounded by reticular fibers. 2- Septa: thin. 3- Reticular C.T. Oxyphil cells Chief cells C.T. stroma in older adults - They are arranged in groups or - are slightly eosinophilic. often contains many adipose clusters or as isolated cells. - are rich in rER. cells. - They are deep eosinophilic They secrete parathyroid Adipose cells may increase with age (acidophilic) hormone( blood calcium). - They have more numerous mitochondria - They are less numerous but larger than chief cells. - They are of unknown function N.B. They may be inactivated chief cells. Histology team 437 | Endocrine block | Lecture two & three  QUESTIONS: Q1: What is the epithelium of thyroid follicles? A) Simple columnar epithelium B) Simple squamous epithelium C) Simple cuboidal epithelium D) Simple stratified epithelium Q2: What type of cells is responsible for the secretion of T4 & T3? A) Clear cells B) Principal cells C) Both of them D) None of them B 6- C 5- Q3: What is the structure whose apices do NOT reach the follicle lumen? A 4- A) Capsule B) Follicular cells C) Parafollicular cells D) None C 3- B 2- Q4: What are the cells that can be found singly or in clusters? C 1- A) Clear cells B) Principal cells C) None D) All of them Q5: Which part of thyroid gland stroma, is thin CT with rich capillary plexus? A) Septa B) capsule C) reticular fibers D) none Q6: What is the cell responsible for the secretion of Calcitonin? A) follicular cells B) parafollicular cells C) All of them D) none Histology team 437 | Endocrine block | Lecture two & three Q7: Which one of the following produce parathyroid hormone? A) Follicular cells B) Parafollicular cell C) chief cells D) oxyphill cells Q8: Which of the following is a Characteristic of oxyphil cells? A) Rich in rER B) abundant mitochondria C) smaller than chief cells D) slightly eosinophilic Q9: Which of the following is a Characteristic of chief cells? 11- D A) Rich in rER B) abundant mitochondria C) basophilic D) All of them 10- B 9- A 8- B Q10: Which of the following is not a histological structure found in parathyroid 7- C gland? A) Chief cells B) colloid C) reticular fibers D) oxyphil cells Q11: Which cell has an un-known function and has numerous mitochondria? A) Follicular cells B) Parafollicular cell C) chief cells D) oxyphill cells Histology team 437 | Endocrine block | Lecture two & three  Team members : Fahad Alnuhabi Ebtesam Almutairi Tareq Allhaidan Shahad Alzahrani Abdulmalik Alharbi Team leaders : Khalid Fayez Alshehri Rinad Alghoraiby Marwah Alkhalil Twitter.com/Histology437 [email protected]